To ensure reproducible results in research and biotechnical processes, today's scientists and clinical practitioners have found it necessary to genetically stabilize living cells and preserve the integrity of complex molecules for storage and transport. This is accomplished by containing these materials in enclosures where cryogenic temperatures are continuously maintained at or near liquid nitrogen or vapor phase liquid nitrogen temperatures (77K and 100K respectively).
Advances in cryopreservation technology have led to methods that allow low-temperature maintenance of a variety of cell types and molecules. Techniques are available for the cryopreservation of cultures of viruses and bacteria, isolated tissue cells in tissue culture, small multicellular organisms, enzymes, human and animal DNA, pharmaceuticals including vaccines, diagnostic chemical substrates, and more complex organisms such as embryos, unfertilized oocytes, and spermatozoa. These biological products must be transported or shipped in a frozen state at cryogenic temperatures to maintain viability. This requires a shipping enclosure that can maintain a cryogenic environment for up to 10 days and meet other shipping requirements such as being relatively impervious to mechanical shock and effects of directional orientation.
In addition to the already existing difficulties posed in shipping heat-sensitive biologicals, the International Air Transport Association (IATA) imposed new regulations which became effective in January 1995 pertaining to all shipments that include specimens containing infectious agents or potentially infectious agents. These regulations, endorsed by the US Department of Transportation (DOT) and applicable to all public and private air, sea, and ground carriers, imposed greatly increased requirements upon shipping units to survive extensive physical damage (drop-testing, impalement tests, pressure containment tests, water damage) without leakage and without fracture of the internal containers (vials). Implementation of this regulation further complicated the shipping of frozen biologicals.
Even though bioshippers are currently available using LN2 as a refrigerant, little innovation has taken place in the design of packaging for low-temperature transport. Current shippers are generally vulnerable to the physical damage and changes in orientation encountered during routine shipping procedures. Additionally, these shippers do not comply with the IATA Dangerous Goods Regulation (effective January 1995, or as later amended). Commercial vendors have not developed or certified a cost-effective, standardized shipping unit with the necessary specimen capacity and hold time to meet user demands.
One of the main criticisms of current shippers is price, which varies from $500.00 to $1,000.00 per unit. This substantially limits their use for the transport of many biologicals. Because of the initial cost and limited production of these containers, they are designed to be reusable. However, the cost of return shipping of these heavy containers is significant, particularly in international markets.
Users also complain about the absorbent filler used in the current dry shippers, which breaks down with continuous use, contaminating the interior of the container. In fact, one large user of these containers has essentially centered their entire shipping operation around cleaning the broken down absorbent material from the inside of these containers after each use.
Another problem cited by users of currently available dry shippers relates to the functional hold time vs. static hold time. Static hold time pertains to a fully charged shipper with no heat load, sitting upright, e.g., essentially not in use. Functional hold time refers to the fully charged shipper in use and containing samples, e.g., in the process of being handled and transported. Even though the static hold time is promoted as being 20 days, if the container is tilted or positioned on its side, the hold time diminishes to hours as opposed to days. This occurs because the LN2 transitions to the gaseous (vapor) phase more rapidly resulting in outgassing. The LN2 can also simply leak out of the container when its positioned on its side.
The current cryogenic containers are promoted as being durable because they are of metal construction. However, rugged handling frequently results in the puncturing of the outer shell or cracking at the neck, resulting in loss of the high vacuum insulation. This renders them useless. The metal construction also adds to the weight of the container, thereby adding substantially to shipping costs.
Due to these deficiencies, and the realization that this current type of cryogenic shipper is not able to meet price and shipping rate goals, and that the biotechnical industry has become dependent on only one flawed system for solving cryogenic shipping demands, there is a need for a more reliable, less expensive, lightweight, semi-disposable cryogenic shipping container. By using unique, lightweight, low-cost, durable composites and polymers, the semi-disposable vapor phase LN2 bioshipper according to the present invention overcomes the above-mentioned disadvantages of the prior art. This is accomplished in an inherently simple, reliable, and inexpensive device which will result in reduced shipping costs, enhance reliability and safety, and fewer service requirements.